It's possible that the terms were never originally intended to be pejorative. Having a shorthand way to refer to people born during certain periods of history not only provides a chronological shorthand, but it allows us to infer some cultural context. If someone's identified as a baby boomer, their childhood likely didn't include Super Soakers or AOL chat rooms. They're statistically likely to have different opinions from more recently-born folks about a number of topics. We can, of course, raise similar arguments about different racial or ethnic groups. There are objective differences in cultural context between groups, even when we ignore the obvious physical differences (i.e., baby boomers are older than Millenials, just like Native Americans have different skin tones than people with recent European ancestors).
The problems arise when the generalizations become interpretations. Any generalization of human beings is inherently dehumanizing. It's an unavoidable element of living in a modern society, though the relationship between personal identity and broader ethical concerns only really began in the mid 1600s. That's really a distinct topic -- even so, it illustrates the difficulties involved in reconciling individual identity with the identities of the Many. We can draw conclusions about one person says or does and what groups of people generally say and do, but using the group as a model for the individual is nigh-impossible when there is high variance among group members.
Really, I'm just tired of glossy stories about Millenials. I'm tired of TIME Magazine's offerings, even when they're chock-full of Joel Stein's usual everyman sarcasm. I'm tired of Atlantic pieces about how self-centered these Millenials are supposed to be (spoiler: youth is a great time for narcissism).* I'm tired of Slate articles which may be unintentional satire, as this quote may reveal:
A generation ago, my college peers and I would buy a pint of ice cream and down a shot of peach schnapps (or two) to process a breakup. Now some college students feel suicidal after the breakup of a four-month relationship. Either ice cream no longer has the same magical healing properties, or the ability to address hardships is lacking in many members of this generation.Isn't hindsight wonderful? I'd love to be able to labor under the pretense that This Generation Is Broken, but I suspect that humanity just generally can't handle hardships well. At best, they can imagine a fantastical, pain-free past.
*I won't even get started on the monthly NYT articles about That Thing Gen Y Does. A slightly more acerbic Slate article than the above one may have to suffice.